The injection of a liquid into the colon by way of the anus is commonly referred to as an enema and is used in a variety of therapeutic and pre-surgical procedures. However, due to the nature of the enema, there is a strong resistance by patients to the use of an enema, even though the therapeutic and pre-surgical procedures are often well-advised. A primary cause for this resistance to the enema is the difficulty and inconvenience of self-application of the enema and the corresponding often required assistance for application of the enema. In addition, there is substantial resistance to the use of an enema which is applied by re-usable devices, since these devices not only suffer from the psychological impact of prior use but require cleaning after use.
To mitigate these difficulties associated with enemas, the art has proposed a number of disposable enema devices, which avoid the above-noted psychological impact of prior use and the requirement for subsequent cleaning. Some of the proposed devices, in addition to being of a disposable nature, are constructions which can be referred to as self-application devices, but these devices are either difficult to operate in a self-application mode or are inconvenient for self-application due to special considerations which must be observed in that self-application. These devices also involve direct contact or close proximity to the anal opening during administration which increases psychological user resistance.
In this latter regard, gravity feed devices have been proposed wherein the devices are composed of, essentially, a disposable plastic bag reservoir for the enema fluid, discharge tubing and a nozzle at the end of the discharge tubing. Various valving arrangements have been proposed for expelling the enema fluid from the reservoir through the tubing and through the nozzle into the rectum. Variations of these devices include provision for manually squeezing the reservoirs to further force enema fluid from the reservoir through the tubing and nozzle. Representative of this art is U.S. Pat. No. 2,784,716. As can be appreciated, however, these devices are quite bulky and difficult to handle. The reservoir must either be supported by some independent mechanical means or it must be held in one hand while the tip of the device is inserted into the rectum. Insertion becomes difficult if the reservoir is held by one hand since the other hand of the user cannot conveniently both separate the buttocks and insert the tip into the rectum. Special lubricated tips, shapes thereof and the like have been proposed to mitigate this problem, but these improvements have proven somewhat unsatisfactory.
Another approach in the art is to provide a small reservoir to which the insertion nozzle is directly attached. These devices are relatively large and difficult to manipulate, especially by one hand.
In U.S. Pat. No. 3,882,866, background of the above nature and prior U.S. patents directed to the art are discussed in some detail, the disclosure of which patent is incorporated herein by reference. That patent goes on to propose a disposable enema device which is a combination of a piston/barrel-type syringe and a lubricated cannula attached thereto. The enema fluid is dispelled into the rectum through the cannula by digitally forcing the piston into the barrel of the syringe by way of a plunger. A major feature of that invention is using the removed rigid cannula cover as the plunger for the piston whereby a more compact unit may be provided. Self-application or use of the syringe with only one hand is not specified in that patent.
It would be, of course, most valuable in the art to provide a syringe of the nature disclosed in U.S. Pat. No. 3,882,866, but which is so arranged that it is more amenable to self-application and, preferably, can be operated by the user with only one hand, thus leaving the other hand available for more comfortable insertion of the cannula. The present invention provides a syringe of that nature.